This invention relates to pressure-sensitive adhesive tapes, adhesive tabs formed therefrom, and methods for manufacturing the same. In one aspect, the invention relates to improvements in transfer tapes and like products, and in the manufacture of the same. In another aspect, the invention relates to improvements in laminate web constructions of diaper fastener-tab stock of the kind adapted to be supplied to a diaper manufacturer and to be separated by the manufacturer into individual diaper-fastening tabs and applied to individual diapers, usually two tabs to a diaper for infant diapers and six tabs to a diaper for adult diapers. In this aspect, the invention particularly relates to means forming part of the diaper tabs and providing novel conveniently manipulated fingerlifts for the tabs.
It has been previously proposed to make articles from pressure-sensitive adhesive tapes in which the layer of pressure-sensitive adhesive is partially covered with a printed pattern of ink.
In U.S. Pat. No. 3,159,930 to Allen et al., a pressure-sensitive tape has a layer 5 printed on the adhesive face. This layer combines adhesive masking and indicia functions, the indicia being in the form of negative images in the mask. The masking layer masks most of the adhesive at the centers of the document-containing articles which are to be cut from the tape, but leaves the adhesive exposed at the edges of the articles. The tape is combined with a release liner.
In U.S. Pat. No. 3,874,893 to Cherrin, which is similar to Allen et al., one or more layers of ink or xe2x80x9coverprint lacquerxe2x80x9d or xe2x80x9ca coating which through solvent or other action causes the adhesive to lose most of its adhesive propertiesxe2x80x9d are applied to the adhesive side of a tape using a flexographic press. When two printed layers are used, the first consists of printed indicia and the second of a background layer which is patterned to leave the adhesive exposed at the edges of document-containing articles which are to be cut from the tape. The background layer functions to mask the adhesive so as to render it non-adhesive at the printed areas. In one embodiment, additional spaced patterns 56 (FIGS. 12 and 13) are printed on the adhesive to function as corner lift tabs when the tape is cut into individual articles. However, the great majority of the cutting of the tape is done directly through the adhesive at unprinted areas thereof, thereby leaving unprinted adhesive directly exposed at the side edges of the tape.
In U.S. Pat. No. 4,068,028 to Samonides, indicia are printed on the adhesive layer of transparent pressure-sensitive labels. These indicia are visible but xe2x80x9cburiedxe2x80x9d and protected when the labels are applied to a mounting surface. In a variant, the labels are opaque, and indicia are printed both on the adhesive layer and on the face side of the label. When the label is mounted on the inner side of a glass window or the like, the indicia on the adhesive side are visible from the exterior side of the window and the indicia on the face side are visible from the interior side.
In U.S. Pat. No. 4,107,811 to Imsande, a tacky floor mat consists of a stack of adhesive-coated sheets peelably joined to each other. To provide lift tabs for the sheets, xe2x80x9ca thin coating of non-adhesive material 18 is print-depositedxe2x80x9d (col. 3, line 61) in a pattern on the adhesive-coated web material from which the sheets are to be cut. The adhesive-coated web material with the patterned coating 18 thereon is then laminated to itself to form a multilayer web (presumably with the pattern of non-adhesive material 18 maintained in register, layer to layer). The laminated material is then cut to sheet size in such manner that the patterned non-adhesive material 18 ends up at the corners of the stacked sheets. non-adhesive material may be of a different color than the sheets.
In U.S. Pat. Nos. 4,671,003 and 4,787,158 to Vitol, removable pressure-sensitive sign stock is backed with release liner which has been perforated at regular intervals, the perforations being in the form of round openings where the adhesive is exposed. Talc or other adhesive masking material is applied to the adhesive at the areas of these openings, and the stock is then slit in both directions to form individual signs of rectangular or other shape each having one or more starting tabs at one, two or four corners. Circular labels are also disclosed having wedge-shaped non-adhesive areas, but how the corresponding perforations in the liner relate to the circular label shape, and how the circular labels are formed from the label stock is not apparent.
Various fingerlift arrangements specific to diaper tabs are also known in the prior art. One simple arrangement is to provide an adhesive-free zone at the fingerlift edge, as in U.S. Pat. No. 3,833,456 to Reed et al. This fingerlift edge can be difficult to grasp; there is no clear indication of the presence of a fingerlift, and the unsupported edges of rolls from which such tabs are cut can be easily damaged.
Another fingerlift arrangement for a diaper tab is a fold-over arrangement, as in U.S. Pat. No. 3,893,460 to Karami. If such folding-over is done during manufacture of the diaper fastener stock, differences in thickness are created across the width of the stock, causing distortions when the stock is rolled up for storage and shipment. On the other hand, if the folding-over is delayed only to be attempted on the diaper line, the difficulty of performing that step as part of the fastener dispensing and application procedure on the diaper line presents a risk of line stops and delays in diaper production.
Another known fingerlift arrangement for a diaper tab is a strip lamination, as in U.S. Pat. No. 4,726,971 to Pape et al. The laminated strip extends outwardly of the width of the diaper fastener stock, so that when the same is rolled and transported, the laminated strip can be easily damaged. Also, the strip creates local thickness variations in the roll.
Still another arrangement is a pull string, as in U.S. Pat. No. 4,005,713 to Mesek. This too may cause thickness variations, and may be complicated to fabricate and manipulate, particularly at high diaper line speeds.
Like the first six prior-art references listed above, the present invention also involves the making of articles from pressure-sensitive adhesive tapes in which the layer of pressure-sensitive adhesive is partially covered with a printed pattern of an adhesive barrier or ink. However, in the present invention as it relates to transfer tapes, the printing is along a continuous zone or line, and the tape is formed in whole or in part by slitting along that continuous line through the tape substrate, an adhesive coating, and the printed barrier. In the present invention as it relates to diaper tabs, an adhesive barrier or ink is used to form end fingerlifts for the tabs.
In one aspect, the present invention involves the concept of utilizing such means to eliminate or minimize complications, constraints and disadvantages involved in pattern-coating substrates with pressure-sensitive adhesive in the manufacture of transfer tapes and other articles. In particular, the invention minimizes or eliminates complications, constraints and disadvantages involved in the need to pattern-coat the adhesive as it is applied in order to allow slitting at one or more intermediate locations across the width of the line to define a specific tape width or widths, and in order to provide adhesive-free and therefore xe2x80x9cpickxe2x80x9d-free roll edges.
The invention overcomes the present inability to slit rolls of premanufactured transfer tape stock to various widths on demand, and eliminates the corresponding need to manufacture and inventory various widths of transfer tape pending demand for one or the other specific width or widths. The invention enables the manufacture of tape stock and tapes of substantially uniform thickness from one edge to the other, with attendant advantages to the manufacturer and converter.
In another aspect, the invention provides for the manufacture of diaper fastener-tab stock, and diaper fastening tabs formed from such stock, in a manner compatible with current diaper manufacturing practice, providing improved diaper tabs, and improved tabbed diapers, at little or no increase in costs over the practices of the prior art.
In this respect, the present invention provides diaper tab fasteners having fingerlifts (i.e., end tabs for the tab fasteners themselves) which are xe2x80x9cbuilt-in,xe2x80x9d which are easy and convenient to use, which overcome the problems of the prior-art diaper tab fingerlifts listed above, and which offer new advantages including the ability to economically provide improved distinguishability of the fingerlifts from the remainder of the tabs, the ability to provide for the absorption of finger oils or other contaminants, and the ability to add fragrances to the tabs.
In respect of the manufacture of diaper fastener-tab stock with xe2x80x9cbuilt-inxe2x80x9d end tabs, the invention provides a variant or alternative to the design of diaper fastener-tab with built-in end tab taught in U.S. patent application Ser. No. 07/710,690, filed Jun. 5, 1991, of common assignee.